# LM1117

**Texas Instruments** · 800 mA LDO regulator (fixed 3.3 V) · SOT-223

An 800 mA low-dropout linear regulator fixed at 3.3 V, in the SOT-223 tab package, TI's take on the ubiquitous 3.3 V rail supply. It regulates a higher input down to 3.3 V with about 1.2 V of dropout at full load, and includes current limiting and thermal shutdown. Like the AMS1117 it needs a 10 uF output capacitor (tantalum or ceramic) for stability, and the tab is the output and heat path. It also comes in adjustable and other fixed voltages; this page is the fixed 3.3 V. Pinout is GND, VOUT (tab), VIN.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | ADJ/GND | input | Adjust pin for the adjustable (LM1117-ADJ) option: connects to the top of an external resistor divider from VOUT to set VOUT = 1.25 V x (1 + R2/R1); adjust-pin current is 60 uA typical (120 uA max over temperature). For fixed-voltage options this pin is ground (0 V reference). |
| 2 | VOUT | power_out | Regulated output voltage pin, up to 800 mA of load current. Requires a minimum 10-uF tantalum capacitor to GND for output stability and transient response. Electrically the same net as pin 4 and the tab. |
| 3 | VIN | power_in | Unregulated input voltage pin, recommended operating range up to 15 V (absolute max 20 V to GND). Must be at least VOUT + 1.2 V (dropout at 800 mA) for the regulator to remain in regulation. Bypass with an input capacitor close to the pin. |
| 4 | VOUT | power_out | Regulated output voltage pin (same net as pin 2 and the SOT-223 tab). Included on the SOT-223 (DCY) package as a second output lead to help distribute the 800 mA output current. |

## Key specifications

| Parameter | Value |
|---|---|
| Type | Fixed LDO linear regulator |
| Output voltage | 3.3 V (fixed) |
| Output current | 800 mA |
| Dropout | 1.2 V max at 800 mA |
| Protection | current limit + thermal shutdown |
| Output cap | 10 µF (stability) |
| Pinout | 1=GND, 2=VOUT (tab), 3=VIN |
| Package | SOT-223 |

## Ordering variants

Same part, different packaging or reel option.

- `LM1117MP-3.3 (SOT-223)`
- `LM1117MPX-3.3 (SOT-223, tape & reel)`

## CAD (KiCad official)

- Symbol: `Regulator_Linear:LM1117DT-3.3`
- Footprint: `Package_TO_SOT_SMD:SOT-223-3_TabPin2`
- 3D model: SOT-223 (KiCad packages3D)
- 3D model files: `lm1117-etched.step` / `lm1117-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `lm1117.step` / `lm1117.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/lm1117.pdf) (46 pp, sha256 `35892f3a8673fae9`, retrieved 2026-08-17, tier: manufacturer)
- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/lm1117-datasheet.pdf)